What is the ruling on dealing with women who act as marriage brokers via social media, request private information from women to present to men, and receive fees after the marriage is completed, knowing that they are unknown and their trustworthiness is not established?

There is no objection to a woman providing specific information, such as height and weight, to the intermediary involved in a marriage proposal, as long as there is nothing suspicious about the intermediary, and a strong presumption of her seriousness is sufficient. Taking a known fee for intermediation is permissible, and it falls under the category of ju'alah (a stipulated reward for a service).